A House of Lords standards watchdog is to look into a complaint over the expenses of former Labour chairman Lord Clarke of Hampstead, it was announced today.

The clerk of the parliaments, Michael Pownall, said he had referred Clarke's case to the House of Lords sub-committee on lords' interests.

Clarke was told on Friday by the Crown Prosecution Service that he will not face criminal charges over allegations relating to his claims for overnight allowances. Three Labour MPs and one Conservative peer are facing prosecution for false accounting.

But today's announcement raises the possibility that the Labour peer may face some form of parliamentary discipline, if allegations that he claimed expenses to stay in London while returning to his home in St Albans are upheld.

Pownall also announced that he had rejected complaints about the expenses of nine other peers.

Pownall released a letter he sent today to a member of the public who raised complaints about peers expenses last November.

In it, he wrote that he had suspended his examination of Clarke's case because of the police investigation which ended with Friday's announcement.

He added: "As I regard this case as complex and serious, I have today referred the complaint relating to Lord Clarke to the sub-committee on lords' interests for examination."

He also said he had not considered a complaint about the attorney general, Lady Scotland, as she was not entitled to claim under the peers' reimbursement scheme because she was a minister during the period concerned.